DE1254266B - Plasma generator - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CI .:

B23k

H05h; F23d
German KL: 21h-30/01

Number: 1254 266

File number: K 51166 VIII d / 21h

Filing date: October 23, 1963

Opened on: November 16, 1967

The invention relates to a plasma generator with two discharge electrodes.

Plasma generators, also known as plasma flame generators, are designed to produce an electrical Cause discharge. Usually this discharge takes place in an inert or in a reducing one Gas, since erosion of the electrodes should be prevented as much as possible. However, if such a Plasma generator for powder spraying, for chemical high-temperature reactions, spectroscopic Analyzes and the like are used, it is inevitable that substances will also be present in the plasma must be introduced, which erode them when they touch the electrodes. Such substances are to be referred to as "active materials" in the following.

A known such plasma generator consists of two discharge electrodes, an inner one Electrode is designed as a tapering rod and axially in a funnel-like narrowing Piercing of the other, outer electrode engages, from a feed for a first fluid flow coaxially with the rod electrode in the electrode bore hole and from a substantially to the Rod electrode vertical feed for a second, powder-laden fluid flow nearby the discharge path. With this arrangement, the inner electrode is now through the one with the second Fluid flow introduced powder, which is an active material according to the above definition, acted upon. As a result, the internal electrode heated to an extremely high temperature is very burns down quickly. This disadvantage of the known arrangement cannot simply be avoided in this way that the fluid flow loaded with active material is kept as far away from the electrodes as possible because the second fluid flow should be introduced into a plasma of the highest possible temperature, be brought as close as possible to the discharge arc, since this is where the highest plasma temperatures are reached appear. Furthermore, the second fluid stream is deeply immersed in the plasma in the vicinity of the discharge arc also desirable because in this case the reaction time between the plasma and the reaction gas is very long.

The invention is therefore based on the object to provide a plasma generator in which to Reduction of electrode erosion the electrode attachment points of the imported active Material are no longer touched and still the one introduced into the electrode space Plasma generator

Applicant:

Kabushiki Kaisha Hitachi Seisakusho, Tokyo

Representative:

Dr.-Ing. E. Maier, patent attorney,
Munich 22, Widenmayerstr. 5

Named as inventor:

Sachio Takei, Hachioji-Shi;

Manabu Yamamoto, Odawara-Shi (Japan)

Claimed priority:

Japan October 24, 1962 (46,348)

active material penetrates as deeply as possible into the plasma jet. According to the invention this object is achieved solved in that a transverse magnetic field acting on the discharge arc is applied and that the second fluid stream opens into the electrode chamber at a distance from the inner electrode and is directed directly at the discharge arc, opposite to the direction of deflection of the Magnetic field.

Since in the invention, the supply channel for the second fluid flow is arranged so that the fluid flow flows out directly in the direction of the discharge arc, it is achieved that the fluid flow is deep immersed in the plasma up to the hot-best plasma spot. The second characteristic of the Invention, namely that an electromagnetic force acts on the discharge arc, namely such that the pressure exerted on the sheet is opposed to a back pressure against the fluid flow prevents the discharge arc from being washed away by the gas flow. By the invention Supplying the second fluid flow thus results in an extremely intensive heating of the fluid flow achieved. In addition, there is the further advantage that the anode attachment parts Because of the gas pressure always kept away from the mouth of the fluid supply channel and at the Channel mouth opposite side of the anode wall is held. So that becomes the danger contamination of the arch attachment point is significantly reduced and arch stability is increased. The created Magnetic field improves sheet stability

709 688/333

3 4

still further and also keeps the arc between materially to be introduced into the plasma without touching its two attachment points in relation to the active material with the electrode attachment points. Heating of the fluid flow is fixed in the most favorable position, if during the operation described above and also when the flow rate of the flow of an active material contained in the supplied fluid is very high. In principle, it was already known that if the gas flow 8 becomes too large, the electrical discharge arc will be deflected too much to one side by means of a magnetic arc discharge 9. Inherit the magnetic deflection. However, the plasma jet 10 is thus also followed, however, so far only deformed in the case of sheet cutting devices, ie printed on one side, with the results in which the sheet is deflected laterally so that the plasma is mixed with the so that this occurs when cutting Liquefied metal-active material introduced into the plasma does not drip off evenly or incompletely on one of the two cutting edges. Such a can. ger, disadvantageous operation of the plasma flame genes-Further details of the invention result rator is according to the invention, however, with the help of the description and the drawing. In the 15 magnetic poles 6 corrected, which produce a magnetic field // with drawing, an embodiment of the invention of a component perpendicular to the plane of the paper is shown for example, namely shows the single drawing. It follows that a figure in vertical section the essential parts of the so-called "Lorentz force" is exerted on the arc discharge of a plasma flame generator after the discharge, namely by the magnetic field crossing the arc discharge, ao charge 9. The Lorentz force According to the drawing, the illustrated output is generated controllably in one direction, the hijacking form of the invention has a basic structure in opposition to that in which the gas form of a cylindrical electrode 1, which is introduced from stream 8. This correction means that there is no magnetic, conductive material. The measure is the force of an active material electrode 1 is with a gas flow 8 contained centrally in the electrode, which tends to flush the arc discharge cylindrical nozzle 2, also a point 9 to the side, running outward in the electrode, conical through-balanced by the electromagnetic Lorentz force, let 3, the coaxial at its narrower upper end whereby an extreme bending or deflection is connected to the lower end of the nozzle 2, and the discharge path on one side prevents a gas supply line 5 provided of which 30, even if the active outer surface of the electrode 1 is introduced to a point in the material with a very high flow velocity near the connection between the conical through the gas supply path 5. Passage 3 and the nozzle 2 leads. A rod-shaped, accordingly it is possible to mix the active materials pointed electrode 4, which is electrically stripped, extremely well into the plasma,
is coaxially within the conical passage 3 35 Since the electromagnetic force, ie the Lorentz orderer and held, in such a force, and the force of the gas flow, ie the position that it faces the electrode 1. The active material containing gas 8 magnetic poles 6 exerted are embedded in the electrode 1, forces are opposite to each other, is in such a position that their poles are facing the position of the electrode of the lower part of the nozzle 2 generator according to the invention. 40 denfußpunktes 11 determined by the sizes of these two during the operation of the plasma flame forces. If the force of the gas flow exceeds the generator above structure, a discharge 9 electromagnetic force is generated, the base points or attachment points of which are located at the point which is the tip of the rod-shaped electrode 4 and which is shown in the drawing , whereby, as already mentioned above the inner wall of the cylindrical electrode 1, the active material is placed at the arch attachment. A gas stream 7 made of inert gas cannot touch. If, on the other hand, the electromagnetic force is directed upwards through the conical passage 3, the force of the gas flow is conducted. The generated by the arc discharge 9 exceeds the electrode attachment parts high-temperature plasma is carried away by the current 7 of the inert gas shown in the drawing, flows through the nozzle 2 and 50 point opposite point, that is, to which is moved as a plasma jet 10 ejected outside. Side of the mouth of the gas supply line 5. In this case, however, in the generator described above, the active material degassing stream 8, containing an active material, also tends to flush away the electrodes of the gas supply line 4 introduced into the plasma by sustaining gas flow. Accordingly, the electrode attachment point 11 at the electrode base at a point in the vicinity of the inner surface of the cylinder electrode 1 is "flushed away" by the gas stream 8 around the opening of the gas supply line 5 and fixed as shown in the drawing . Accordingly, in this case, too, it is interpreted that the electrode base is fixed at a certain point on the inside without contact with the wall opposite the gas supply line 5. active material.

The gas flow 8 with the active material, which by 60 The described principles and advantages of

the gas supply line 5 has been introduced, generator according to the invention have come through

experiments are then confirmed by the inert gas stream 7 upwards. For example, was water

entrained and atomized together with the plasma jet 10 with the aid of an atomizer into a mist

ejected without the tip of the rod-shaped and in a flow rate of about 5 g / min. Electrode 4 or the electrode attachment point 11 on 65 through the gas supply channel 5 of a generator

the inner wall of the cylinder electrode 1 touch the construction described with water-cooled

could. Accordingly, it is possible to use the above-mentioned copper anode as the cylinder electrode 1 and tungsten To solve the problem, namely an active cathode introduced as a rod electrode 4. As an inert

Claims (1)

Gas stream 7, argon gas was introduced at a flow rate of 20 l / min; the discharge current was 180 amps. The spectrum of the resulting plasma jet 10 was measured under these conditions, and the spectral lines and bands of H, O and OH of the dissociated water could be clearly determined. It has been shown that the intensities of these spectra when a magnetic field H was applied were approximately twice as strong as without an applied magnetic field, the differences between the intensities indicating that the plasma and the water mist were better with one another through the application of the magnetic field be mixed. It has also been shown that a magnetic field strength of 300 to 500 Gauss is suitable for the above purpose. If a magnetic field with a higher field strength than the specified range was applied, the electrode base 11 was formed on the side of the mouth of the gas supply line 4, and if the applied field strength was less than this area, the electrode base was formed on the opposite side. However, it has been shown by spectroscopic investigations that in both cases there is no erosion of the electrodes. Claim: Plasma generator with two discharge electrodes, an inner electrode being designed as a tapering rod and axially engaging in a funnel-like narrowing through hole of the other, outer electrode, a feed for a first fluid flow coaxially with the rod electrode into the electrode through hole and one essentially to the Rod electrode vertical feed for a second fluid flow which can be loaded with powder in the vicinity of the discharge path, characterized in that a transverse magnetic field (H) acting on the discharge arc is applied in a manner known per se and that the second fluid flow (8) is at a distance of of the inner electrode (4) opens into the electrode chamber and is directed directly at the discharge arc, namely opposite to the direction of deflection of the magnetic field. Considered publications: U.S. Patent No. 3,016,447;
British Patent No. 825,677. 1 sheet of drawings 709 688/333 11.67 ® Bundesdruckerei Berlin